Antibiotic dispensing spacer apparatus and method for infected total knee arthroplasty

Abstract

A spacer for a knee replacement prosthesis. The spacer may have a lower surface with a locking component adapted to interlock with a tibial tray, an upper surface optionally with a tibial post and a pair of smooth-surfaced and slightly concave condyle support platforms disposed on opposite sides of the tibial post, and a substantially hollow body with an internal reservoir that can be filled with antibiotic material. The reservoir may be accessible from a port on the hollow body that leads into the internal reservoir, and which permits refilling of the reservoir. In some embodiments, the reservoir may be refillable from this port without removal of the spacer from the patient; for example, a percutaneous needle may be inserted into the port. The spacer may dispense antibiotic from this reservoir to the surrounding area in order to treat an infection.

What is claimed is: 
     
       1. A spacer for a knee replacement prosthesis, comprising:
 a lower surface, the lower surface comprising a locking component adapted to couple with a tibial tray; 
 an upper surface, the upper surface comprising a pair of condyle support platforms, each of the condyle support platforms being smooth, the surface of each of the condyle support platforms further having a shallow concavity; and 
 a body, the body having a hollow outer portion surrounding an internal cavity, the material of the body being impermeable to fluid; the body further having a port comprising a channel formed of a flexible or fibrous material, the channel extending through the hollow outer portion of the body, and permitting the introduction of fluid through the port into the internal cavity after the spacer is in situ, wherein the fluid to flow into the effective knee space is at a predetermined rate. 
 
     
     
       2. The spacer of  claim 1 , wherein the lower surface is connected to the tibial tray by a nonmechanical connection. 
     
     
       3. The spacer of  claim 2 , wherein the nonmechanical connection is one of grout or bone cement. 
     
     
       4. The spacer of  claim 1 , wherein the lower surface couples with the tibial tray in a temporary fashion. 
     
     
       5. The spacer of  claim 1 , further comprising a central femoral guide on the upper surface. 
     
     
       6. The spacer of  claim 1 , wherein the internal cavity further comprises at least one of a reservoir, pump, and fluid restrictor. 
     
     
       7. The spacer of  claim 1 , wherein the channel further comprises a fluid flow regulation device. 
     
     
       8. A total knee prosthesis, comprising:
 a femoral component comprising a femoral stem adapted to be inserted in an intramedullary canal of a femur, and a pair of condyles; 
 a tibial component comprising a tibial stem adapted to be inserted in an intramedullary canal of a tibia and connected to the femoral component, and comprising a tibial tray; and 
 a spacer, the spacer comprising: 
 a lower surface, the lower surface comprising a locking component adapted to interlock with the tibial tray; 
 an upper surface, the upper surface comprising a pair of condyle support platforms, each of the condyle support platforms being smooth, the surface of each of the condyle support platforms further having a shallow concavity; and 
 a body, the body having a hollow outer portion surrounding an internal cavity, the material of the body being impermeable to fluid; 
 the body further having a port comprising a channel formed of a flexible or fibrous material, the channel extending through the hollow outer portion of the body, and permitting the introduction of fluid through the port into the internal cavity after the spacer is in situ and means for the fluid to flow into the effective knee space at a predetermined rate; 
 wherein the locking component of the spacer is connected to the tibial tray of the tibial component, and wherein each of the condyles of the femoral component is disposed in one of the condyle support platforms of the spacer. 
 
     
     
       9. The total knee prosthesis of  claim 8 , wherein the port permits introduction of fluid into the internal cavity prior to implantation of the total knee prosthesis. 
     
     
       10. The total knee prosthesis of  claim 8 , wherein the port permits introduction of fluid into the internal cavity following implantation of the total knee prosthesis.